Engine Design Research Articles

Conjugate Heat Transfer Advancements and Applications in Aerospace Engine Technology

Over the past few decades, conjugate heat transfer (CHT) technology has been instrumental in predicting temperature fields within aerospace engines, guiding engine design with its predictive capabilities. This paper comprehensively surveys the foundational technologies of CHT and their applications in engine design, backed by an extensive literature review. A novel coupling iteration methodology, su-F-TFTB, was proposed. Following this, it introduced grid splicing technology tailored for heat flux conservation, which significantly enhances the adaptability of CHT grids. Ultimately, this study employed the self-developed Aerospace Engine Numerical Simulation (AENS v4.0.1) software to perform CHT analyses on NASA-C3X turbine blades equipped with ten radial cooling systems. A comparative analysis of pressure distributions across various density meshes was undertaken to affirm mesh independence. Furthermore, the impacts of the Spalart–Allmaras (SA) one-equation model and k–ω Shear Stress Transport (SST) two-equation model on the temperature distribution in conjugate heat transfer were investigated. The results indicated that the k–ω SST model exhibited superior performance, aligning closely with NASA experimental data. This validation confirmed the effectiveness of the software.

A theoretical framework for the analysis of an opposed piston linear engine design

Traditional crank-based engines face limitations due to mechanical, thermal, and combustion inefficiencies. In contrast, the opposed piston design of a linear engine generator mitigates frictional losses by eliminating rotational motion and crankshaft linkages. Instead, electrical power is generated through the oscillation of a translator within a linear stator. However, the lack of geometric constraints in the free piston design leads to uncertainties regarding dead center positions, resulting in challenges such as misfire, stall, over-fueling, and rapid load changes.This study aims to fill this gap by reviewing existing modeling literature and advancing the fundamental understanding of opposed piston linear engines (OPLE) with springs through the development of an idealized, nondimensional model. A combination of analytical and numerical models was developed to better understand the behavior of the OPLE. The model introduces a streamlined symmetric analytical solution, succeeded by a broader general analytical resolution, with careful attention to the significant influence of thermodynamic effects at each phase, offering insights into the engine's dynamic performance. Limitations inherent to the analytical solutions are addressed by a numerical scheme utilizing the Runge-Kutta technique. This approach guarantees swift and dependable computational outcomes, which captures cyclic variation. The alternator model amalgamates both linear and sinusoidal work profiles, adjusting the magnetic work output in response to fluctuations in the compression ratio relative to the Top Dead Center (TDC) clearance distance. This adjustment dictates the generator load for each translator.The proposed model integrates the dynamics of a damped spring-mass system with thermodynamic expressions representing in-cylinder processes. Simplifications are made assuming perfect springs, ideal gases, instantaneous heat transfer, and an average friction force dependent on stroke length for work output. Selected cases are analyzed to elucidate the system's fundamental behavior, both within and outside the context of the Otto cycle, showcasing natural and forced stability over multiple operation cycles. Notably, enhancing the baseline cylinder pressure, or input heat relative to spring stiffness can elevate the work-to-heat ratio values. The attained work-to-heat ratio within compression ratio window of 16 is approximately 28 %. While this percentage may fluctuate in the context of general FPLE designs, the model developed for OPLE in this work plays a crucial role in maintaining the engine within this narrowly defined efficiency range, without compromising the potential performance demonstrated in this study. Differences in compression ratios provided intriguing insights into the dynamics of the translator and the in-cylinder thermodynamics of the interconnected system. Lower TDC clearance resulted in high translator displacement, velocity, and enhanced thermal efficiency.

Aircraft Performance Simulation of 19-Passenger Commuter Aircraft: A Comparison between Normal and Amphibious Category

This article presents calculating flight performance aspects and simulations of flight characteristics during a flight mission of the 19-passenger commuter aircraft, with a focus on the comparison between the normal and amphibious category aircraft. The objective is to analyse the flight characteristics (warm up, takeoff, cruise, descent, landing) and capabilities of both aircraft configurations. The significant difference between the two aircraft lies in the presence of float components in the 19-passenger Amphibious aircraft. The calculation process, both manual and simulation-based, involves utilizing constraint analysis and mission analysis to determine the weight fraction values for each flight phase. The results of the constraint analysis indicate that the amphibious category aircraft has higher values (35% - 80%) compared to the normal category aircraft. Meanwhile, the calculations using aircraft engine design (AEDsys) software reveal nearly identical reductions in weight fraction for each phase, with the amphibious category aircraft having a significant decrease in the final weight fraction of 0.87836. The fuel weight used is 2129 lb or 965.70 kg (8 barrels) with a range of approximately 372 nm or about 690 km and a flight time of approximately 2.4 hours. The drag polar values obtained using Parametric cycle analysis software at an altitude of 3,048 meters (10,000 ft) show that the normal category aircraft has a smaller coefficient drag (CD) value. Further validation of the findings from this performance simulation study can be conducted through direct experimental validation during flight to be utilized for optimizing aircraft performance.

Multidisciplinary Design Methodology for Micro-Gas-Turbines—Part II: System Analysis and Optimization

Abstract Owing to their high specific energy capabilities, ultramicrogas turbines (UMGT) are a high-potential technology to provide portable electric power supply for applications with demand of less than 1 kW. UMGT conceptual design is challenged by small-scale effects augmenting interdisciplinary dependencies leading to highly coupled, nonlinear component interactions. This work provides a novel approach to conceptual UMGT design by combining reduced order component and system modeling with constrained multi-objective optimization. Hereby, Part I presents integrated design and performance modeling of compressor, turbine, combustor, and generator. In Part II, the heat engine and generator modules are merged into a system framework by establishing conceptual UMGT rotor geometry and engine design. Following bearing selection and lifetime assessment, experimentally validated reduced order models are developed for heat transfer and rotordynamic analysis. Using the elaborated framework, a constrained multi-objective system optimization of a 300 W engine is performed based on ten design parameters and comparing SiAlON and Inconel 718 as potential rotor materials available for additive manufacturing. Hereby, bearing lifetime, system efficiency, and specific power are maximized while meeting rotordynamic, structural, and thermal requirements. Evaluating the results, interdisciplinary effects are highlighted, and two optimum engine configurations are suggested.

Optimization of Bypass Flow Introduction Angle in Dual-Throat Nozzle

This research paper investigates the optimal angle for introducing a bypass jet in rocket engines for thrust vectoring. Numerical simulations using a finite-volume method were performed to test a range of bypass jet angles and their effect on flow performance. Results indicate that the optimal bypass jet angle is between 40 and 50 degrees, with larger angles leading to decreased thrust. These findings demonstrate the potential for bypass jet introduction to improving thrust vectoring in rocket engines, especially in the supersonic regime. Such insights may inform the development of more efficient and effective rocket engines for various applications, including satellite launches, space exploration, and defense. Overall, this study represents a valuable contribution to the field of rocket propulsion and may drive advances in engine design and performance.

Influence of gear modification on dynamic characteristics of star gearing system in geared turbofan (GTF) gearbox based on a closed-loop dynamic analysis method

The star gearing transmission system is a key component of a geared turbofan (GTF) aero-engine. Accurate prediction of the dynamic characteristics of the star gearing transmission system, especially after gear modification, is important for the design of high-performance engines. Firstly, this paper establishes a dynamic time-varying mesh stiffness (TVMS) and a comprehensive transmission error (TE) calculation model for herringbone gear pair considering changes in the meshing state. Then, the dynamic internal excitation calculation model is combined with the lumped parameter dynamic model of the system to form the “excitation–response–feedback” closed-loop coupling dynamic analysis method of the GTF star gearing system. Compared with traditional analysis methods, this method takes into account the effect of contact state changes on internal excitation during the calculation process and corrects internal excitation in real time. Finally, the effect of different topology modification schemes on the system's dynamic characteristics is investigated based on this method. The results show that the closed-loop coupled dynamics analysis method is able to capture contact state changes of the same gear pair at different moments and between different gear pairs at the same moment. Modified #2 is only to modify the planet gear. This scheme can effectively reduce the vibration displacement of the ring gear, and reduce the peak-to-peak value of the ring gear's vibration displacement in all directions by more than 70%. At the same time, the scheme also reduces the load-sharing coefficient of the internal and external meshing pairs of the system by 1.92% and 2.01%, respectively, and the peak-to-peak value of the dynamic factor of the internal and external meshing pairs can be reduced by 57.91% at most.

Exergy analysis under consideration of operational parameters by numerical approach in a two-stroke marine diesel engine

This paper presents a numerical approach of the influence of operational parameters on the exergy terms in a two-stroke marine diesel engine. Operational parameters are introduced as different start of injection (-4, -2, 0 and 2 °CA) and scavenge air inlet temperature (300, 312, 330 and 340 K) values. The energy analysis is conducted within a closed cycle by using a three-dimensional computational fluid dynamics code. The simulation results are compared with the corresponding experimental pressure data in the literature and show good agreement. Also, the exergy analysis is performed by a developed in-house computational code. Various exergy rates and cumulative exergies are detected and computed separately at operational parameters. The study reveals that varying the start of injection timing from −4 to 2 °CA at full load condition results in a decrease in exergy efficiency from 43.45 % to 41.36 %. Furthermore, an increase in scavenge air inlet temperature from 300 K to 340 K leads to a reduction in exergy efficiency from 42.83 % to 41.44 %. These findings underscore the critical influence of injection timing and scavenge air temperature on the exergy performance. In light of these results, this paper gains more insight into the impact of design parameters of a two-stroke marine diesel engine on exergy efficiency and presents a preliminary data for marine diesel engine manufacturers in the design of a two-stroke marine diesel engine that uses energy efficiently.

Kinetic Analysis of the Reaction of Micrometer-Sized Al-Mg Alloy Particles in a Water Vapor Atmosphere.

This study investigated the reaction mechanism of aluminum-magnesium (Al-Mg) alloy particles with water (Al-Mg/H2O) through thermogravimetric analysis-differential scanning calorimetry experiments and kinetic analysis using isoconversional methods and the master plot technique to determine the reaction mechanism function, with the aim of providing insights to support metal powder/water ramjet engine design and combustion characteristics. The results showed that the Al-Mg/H2O reaction occurred in two distinct stages, with stage 1 primarily involving the reaction of Mg elements in the L(Al-Mg) alloy with water while Al played a leading role in stage 2. Notably, the reaction temperatures of Al-Mg particles were significantly lower than those for either Al or Mg particles alone in a water vapor environment. Additionally, the activation energy of stage 1 was lower than that for the individual Al and Mg particles and decreased with increasing Mg content in stage 2. Furthermore, the concentration of Mg in the alloy was found to have a major influence on the reaction mechanism, which followed a random nucleation and growth model. Overall, this work elucidated an alternating endothermic and exothermic staged reaction process for Al-Mg/H2O dominated first by Mg and then Al with kinetic insights providing theoretical support for optimizing Al-Mg alloy compositions for improved ignition and combustion performance in metal powder/water ramjet engines.

ENHANCING GAME ENGINE PERFORMANCE THROUGH MULTITHREADING

Today, game engines play a significant role in the modern gaming world, with possible multithreading techniques being pivotal in optimizing gaming performance and overcoming performance bottlenecks. This paper discusses a worthwhile approach to increasing game engine performance by leveraging effective multithreading principles, along with the issues that need to be considered in the design of a multithreaded game engine and aims to contribute to the continuing evolution of game development. Through an ideal integration of data and task parallelisms in a well-balanced engine, developers can fully benefit from the capabilities of multicore processors, resulting in smoother and more responsive gaming experiences. The results obtained from employing both data and task parallelism jointly in the same architecture showed a remarkable performance increase of about 2.3 times faster than the single-threaded model. The paper also addresses common multithreading challenges, such as synchronization issues and load balancing, together with their solutions, emphasizing the effectiveness of the proposed model. Keywords: Multithreaded Game Engine, Multithreading, Game Engine Performance, Multithreading Principles, Data Parallelism, Task Parallelism, Task scheduler.

Research on Scavenging Flow Dynamics of Marine Two-Stroke Engines With a CFD-Derived Quasi-Dimensional Model

The complex in-cylinder gas state and flow significantly affect fuel-air mixture, combustion efficiency and emissions. However, the scavenging CFD model of large bore marine engines in digital twin system requires substantial computational resources. Therefore, a fast-run phenomenological model of the scavenging process is built in this study. The model simulates the thermal states and flow dynamics of inlet and exhaust gas based on the energy and momentum conservation principles, considering the ideal in-cylinder swirl velocity profile with effects of air mass loss, wall friction, and swirl shear. The model’s accuracy is confirmed by comparing it with CFD simulations on different engines, showing an average relative error less than 3.5%. It also analyzes the impacts of intake pressure. The model provides accurate boundary conditions for subsequent fuel spray, combustion, and emission simulations and can be combined with these models in the future, thereby applied to engine design, diagnostics, and control.

Design assessment of the range of permissible operation modes of a marine two-stroke diesel engine

In the practice of operating marine diesel engines, as a limiting characteristic for mechanical stress, a characteristic corresponding to a constant effective torque, which is proportional to the average effective pressure, is used. There is no such unambiguity regarding the restrictive characteristics of thermal intensity. Limitations on the thermal stress of a diesel engine depend on its design features and the efficiency of the cooling system of the cylinder-piston group. At the diesel engine design stage, it is important to assess in advance whether the operational characteristics correspond to the technical specifications.
 The work carried out computational and theoretical studies of the operational parameters of the main marine two-stroke diesel engine operating according to the screw characteristic, which affect its mechanical and thermal stress, and determined the expected limiting characteristics of the mechanical and thermal stress. The studies were carried out for wide ranges of changes in the weight coefficient of the screw characteristics and the relative power of the diesel engine. The estimated design ranges of diesel operating modes are given, excluding its mechanical and thermal overload, and an assessment of the permissible weighting of the screw characteristics is given. The results obtained were compared with the characteristics of a marine four-stroke diesel engine.

Harnessing a Better Future: Exploring AI and ML Applications in Renewable Energy

Integrating machine learning (ML) and artificial intelligence (AI) with renewable energy sources, including biomass, biofuels, engines, and solar power, can revolutionize the energy industry. Biomass and biofuels have benefited significantly from implementing AI and ML algorithms that optimize feedstock, enhance resource management, and facilitate biofuel production. By applying insight derived from data analysis, stakeholders can improve the entire biofuel supply chain - including biomass conversion, fuel synthesis, agricultural growth, and harvesting - to mitigate environmental impacts and accelerate the transition to a low-carbon economy. Furthermore, implementing AI and ML in combustion systems and engines has yielded substantial improvements in fuel efficiency, emissions reduction, and overall performance. Enhancing engine design and control techniques with ML algorithms produces cleaner, more efficient engines with minimal environmental impact. This contributes to the sustainability of power generation and transportation. ML algorithms are employed in solar energy to analyze vast quantities of solar data to improve photovoltaic systems' design, operation, and maintenance. The ultimate goal is to increase energy output and system efficiency. Collaboration among academia, industry, and policymakers is imperative to expedite the transition to a sustainable energy future and harness the potential of AI and ML in renewable energy. By implementing these technologies, it is possible to establish a more sustainable energy ecosystem, which would benefit future generations.

Enhancement of the lubrication system of an internal combustion engine

BACKGROUND: The modernized design of the lubrication system with an individual electric-driven oil pump ensures the oil supply to remote and loaded parts, regardless of the crankshaft speed, starting mode and engine warm-up. AIM: Study of the main directions for enhancement of the lubrication systems of piston engines in order to assess the option of using an autonomous electric drive. METHODS: The design of an adjustable inductor electric drive with microprocessor control is proposed as a drive. The ability to keep rotation speed of the pump gears accurately is ensured using a controlled inductor electric motor, depending on the pressure in the lubrication system. RESULTS: The design and technological implementation of the proposed method of driving an oil pump does not require major changes to the engine design. The layout of the oil pump at the engine is simplified. CONCLUSIONS: The proposed design of the lubrication system of an internal combustion engine ensures optimal rotation speed of the pump shaft regardless of the operating modes of the piston engine, resulting in an increase in engine operating life.

Aircraft engine danger areas incursion detection using keypoint detection and IoT

Operational safety at airports has long been a subject of active research, with a growing focus on the safety of aircraft stands in recent years. The phase during which an aircraft taxi into its designated stand with engines still running poses safety risks to surrounding vehicles. However, there is currently a lack of effective methods for detecting potential conflicts and hazards during this taxiing phase. To address this issue, this study utilizes apron activity videos as a monitoring data source and introduces an integrated Internet of Things (IoT) conflict detection model. This system combines object detection, engine keypoint detection, coordinate conversion, and conflict warning system to provide timely alerts when vehicles incursion into the engine danger areas. Firstly, the paper streamlines the fourth-level branch and network of HRNet, resulting in the HRNet-3stage network. This network is then compared with Lite-HRNet to determine the optimal choice. Secondly, Recognizing the limitations of traditional video conflict detection based on pixel distance, a fixed monitoring camera coordinate conversion algorithm is designed to convert pixel coordinates into actual coordinates on the aircraft stand, thereby improving the accuracy of conflict detection based on distance measurement. Thirdly, considering the risks associated with engine inlet and exhaust, engine design parameters, static spacing standards, and the dynamic anti-collision process within the aircraft stand, the study proposes a method for classifying four types of aircraft engine danger areas. Corresponding conflict detection models are designed for potential scraping incidents when vehicles incursion into these danger areas. Upon detecting a vehicle entering the aircraft engine danger areas, the IoT system sends warning messages through the airport control tower monitoring system. Finally, we construct an apron sandbox to validate the conflict detection model. This validation results in an impressive F1-score exceeding 90% and a detection delay of less than 100 ms. Our innovative approach, supported by keypoint detection networks and IoT, effectively addresses the detection of critical aircraft components within stands. It comprehensively analyzes incursion issues into engine danger areas, offering a novel perspective for understanding and mitigating potential conflicts arising from aircraft taxiing into stands.

Efforts to Improve Ship Main Engine Efficiency and Ensure Its Safety

Efforts to improve ship main engine efficiency and ensure its safety have been ongoing endeavors in the maritime industry, driven by the dual imperatives of economic competitiveness and environmental sustainability. The main engine of a ship serves as its heart, propelling it through the vast expanses of the world's oceans while consuming significant quantities of fuel. Therefore, enhancing its efficiency directly impacts operational costs and reduces the environmental footprint associated with maritime transport. One primary focus of improving main engine efficiency lies in the advancement of engine design and technology. Over the years, there has been a concerted effort to develop engines that offer higher power output while consuming less fuel. This has led to the emergence of more efficient engine designs, such as slow-speed two-stroke engines and high-pressure, common-rail fuel injection systems. These innovations optimize fuel combustion, minimize energy losses, and enhance overall propulsion efficiency. Moreover, ongoing research and development efforts are aimed at harnessing alternative fuels and propulsion technologies to further enhance efficiency and reduce environmental impact. LNG (liquefied natural gas) has gained traction as a cleaner-burning fuel alternative, offering significant reductions in sulfur oxides (SOx) and nitrogen oxides (NOx) emissions compared to traditional marine fuels. Additionally, the exploration of hybrid and electric propulsion systems holds promise for reducing greenhouse gas emissions and improving overall energy efficiency. Ensuring the safety of ship main engines is paramount to the reliability and operability of vessels at sea. A robust maintenance regimen is essential to identify and address potential issues before they escalate into costly failures or pose safety hazards. Routine inspections, preventive maintenance, and condition monitoring play crucial roles in detecting abnormalities, wear, and tear, allowing for timely interventions and repairs. Furthermore, advancements in predictive maintenance technologies, such as remote monitoring systems and data analytics, enable real-time assessment of engine performance and early detection of potential malfunctions. The ARAS method lacks the capability to handle ambiguity, subjective judgments, and coping with incomplete information. It relies on unbiased good judgment to address uncertainty, particularly in unknown and complex conditions, making it a valuable approach. The method provides options for sequencing and analysis based on facts and special cases, allowing selectors to express both optimistic and rational attitudes. While it appears numerical on paper, it offers the flexibility to create e-learning pathways tailored to individual needs, emphasizing the importance of mastery. The proposed integrated software for this method is both cost-effective and validated for suitability, ensuring its practical application. Advanced Engine Designs, Improved Monitoring and Maintenance, Enhanced Fuel Management, Innovative Propulsion Technologies, Automation and Remote Monitoring and Advanced Materials and Coatings. the Rank Efforts to improve ship Main Engine efficiency and Ensure its safety for Additive Ratio Assessment method. Advanced Materials and Coatings is showing the highest rank and Advanced Engine Designs is showing the lowest rank. Fuel Efficiency Improvement, Emissions Reduction, Reliability and Maintenance Costs and Safety Performance.

Low-order modeling approach for the prediction of transverse combustion instabilities in multi-injector engines

This paper addresses the prediction of spontaneous self-sustained transverse combustion instabilities in multi-injector engines using a multi-dimensional non-linear low-order Eulerian model. The approach utilizes a physically aware response function that directly links pressure oscillations to fuel mass flow rate, independent of external data. This enables accurate capture of the behavior of shear coaxial injectors that have been proven to show a peculiar dynamics of cyclic fuel accumulation and release in response to acoustic waves. A NASA test case is employed as a reference, and a comprehensive analysis is conducted to investigate the behavior of the model. Firstly, a preliminary analysis is performed within a quasi-one-dimensional framework for a reduced single-injector configuration. This analysis provides insights into the influence of key parameters on the instability onset. Subsequently, the full-scale geometry is considered in a multi-dimensional framework, and the low-order solver is employed to analyze the thermo-acoustic behavior of the engine. The model successfully captures the instability dynamics, including temporal evolution, dominant frequency, and mode shapes. Sensitivity analyses are conducted to examine the impact of the model free parameters on the unstable modes. Additionally, the effect of introducing baffles as damping devices within the combustion chamber is investigated. The results highlight the model predictive capabilities and its potential for guiding the design and optimization of liquid rocket engines.

Ammonia marine engine design for enhanced efficiency and reduced greenhouse gas emissions

Pilot-diesel-ignition ammonia combustion engines have attracted widespread attentions from the maritime sector, but there are still bottleneck problems such as high unburned NH3 and N2O emissions as well as low thermal efficiency that need to be solved before further applications. In this study, a concept termed as in-cylinder reforming gas recirculation is initiated to simultaneously improve the thermal efficiency and reduce the unburned NH3, NOx, N2O and greenhouse gas emissions of pilot-diesel-ignition ammonia combustion engine. For this concept, one cylinder of the multi-cylinder engine operates rich of stoichiometric and the excess ammonia in the cylinder is partially decomposed into hydrogen, then the exhaust of this dedicated reforming cylinder is recirculated into the other cylinders and therefore the advantages of hydrogen-enriched combustion and exhaust gas recirculation can be combined. The results show that at 3% diesel energetic ratio and 1000 rpm, the engine can increase the indicated thermal efficiency by 15.8% and reduce the unburned NH3 by 89.3%, N2O by 91.2% compared to the base/traditional ammonia engine without the proposed method. At the same time, it is able to reduce carbon footprint by 97.0% and greenhouse gases by 94.0% compared to the traditional pure diesel mode.

Quantum Propulsion: Background and Practical Applications

This is the first introduction of new and revolutionary aerospace engines and propulsion methods. Our organization is currently developing quantum propulsion systems and space vehicles that will be capable of flying with enormous speed (potentially reaching and exceeding the speed of light) and will have unseen-before manoeuvrability and lifting capacity. They will provide 100% crew protection from deadly sun and space radiation which is essential for safe deep space travel and manned space exploration. They will also provide spacecraft with protection against space particles. To date, we have managed to crack the main secret of practical quantum engine design and we are ready to develop it further into fully operational aerospace vehicles. Quantum propulsion systems are the only systems that can facilitate realistic prospects of space mining on the industrial scale and deep space colonisation, including colonisation of habitable planets in the future. The cost efficiency of this new technology is going to be enormous. Development and production costs of quantum aerospace vehicles compared to production costs of chemical fuel jet spacecraft allow to reduce price per kilo space launch ratio hundreds of times, making deep space exploration and commercialisation more accessible and practically feasible at last. Manufacturing and maintenance of quantum-propelled flying machines that can reach the age of our solar system within hours will be no more expensive than manufacturing jet planes or helicopters of the same size. Quantum propulsion systems are going to replace outdated chemical fuel rocket and jet engines in the near future and will become the mainstay of air travel and space exploration.

Numerical model of variable valve timing distribution for a supercharged diesel engine

Recently, there's been a strong drive to improve performance of diesel engines while reducing their greenhouse gases emissions. Techniques like exhaust gas recirculation, turbocharging, and variable valve timing have become widespread. The last technique fine-tunes valve operation based on engine speed, which optimize efficiency and power output while saving fuel. This study zeroes in on a specific 4-cylinder, 4-stroke diesel engine of 1.56-liter, GT-Power software is employed to examine a supercharged version and implementing diverse valve lift techniques. The findings are revealing a substantial 30% increase in power output. At 1000 rpm, power rises from 15.1 kW for the standard engine to 19.72 kW for the modified version. For higher engine speeds, the improvements become even more pronounced, reaching a 66% boost compared to the standard configuration. Furthermore, the newly configured engine showcases an impressive 13% decrease in fuel-specific consumption at elevated engine speeds, contributing to enhanced technical performance and fuel efficiency. The numerical model developed in this study holds the potential to aid in the design of novel diesel engines equipped with variable valve timing systems. To lend further support to these findings, experimental validation is recommended.

Numerical study of film cooling in single-element injector gaseous CH4/O2 rocket engine with coupled wall function

The investigation of film cooling in CH4/O2 rocket engines holds paramount importance in the advancement of rocket propulsion. However, the wall heat flux is always overestimated in numerical simulation processes. Hence, this article proposes a numerical framework that employs the Reynolds averaged Navier–Stokes method to simulate the single-element gaseous CH4/gaseous O2 combustion chamber, which is the basis for rocket engine simulations. The coupled wall function that considers chemical reaction effects is introduced to enhance the accuracy of wall heat flux prediction. The impact of utilizing a coupled wall treatment on the prediction of wall heat flux and its fundamental parameters are examined. In addition, a single-element combustion chamber experiment is performed to validate the simulation. The results demonstrate that the implementation of the coupled wall function hardly influences the main flow characteristics, whereas the wall heat flux calculated with general wall functions shows an overestimation, which can be reduced by the coupled wall function. Finally, the case with a coupled wall function can improve the cooling efficiency with greater accuracy and the cooling systems with optimized design. The proposed numerical framework and the findings of the study provide profound insights that can improve the design and optimization of rocket engines.